One trend at this year's event was hybrid and electric trucks, including the hybrid delivery truck at the far left of the frame, which Staples just received. The company, which hosted the conference, is also testing an all-electric delivery truck made by Smith Electric Vehicles. This technology is well suited to deliveries because the stop-and-go nature of the driving allows the batteries to be recharged during braking. See this video for more details. In the foreground on the right is the front of Ford's Transit Connect van. Ford plans to release an all-electric version next year.

Not your father's hybrid

This truck was one of many diesel hybrids that were on display at the AltWheels Fleet Day. Using a hybrid power system made by Eaton along with the diesel engine improves fuel economy by 60 percent, according to Eaton.

Hybrid bucket truck

Eaton was also the supplier for the hybrid power system in this bucket truck, another diesel hybrid. The operator of the bucket said that hydraulics work more smoothly than typical bucket truck controls.

Altwheels fleet day aerial

Here's the view from the AltWheels Fleet Day from above. On the bottom right are two Volkswagens converted to run on compressed natural gas, which were custom jobs. At the end of the row on the left is Staples' all-electric delivery truck made by Smith Electric Vehicles.

Primary hybrid components

The electronic components that go into a hybrid diesel truck are the same as a hybrid sedan, only much bigger. Like hybrid sedans, these trucks improve fuel economy by using the battery during acceleration and recharge the batteries when the vehicle decelerates or the driver steps on the brakes.

Hydraulic hybrid garbage truck

Battery-assisted trucking was not the only technology on display. This garbage truck, one of only a handful, uses a pressured hydraulic tank to store energy. Pressure in the tank is built during braking and then released to power the truck during acceleration. The pressure in the tank is over 1,800 pounds per square inch. The hydraulic-assist technology adds about $40,000 to a truck that costs about $250,000. The fuel efficiency improvement from this system is about 20 percent.

Plug-in hybrid escape

More familiar hybrids are also being used as part of larger fleets. National Grid is one of a number of utilities testing how plug-in electric vehicles affect the demand for electricity on the grid and how these vehicles can be tapped by utilities for short-term storage. Among the cars being used in the trial programs is this Ford Escape SUV, which has been converted into a plug-in with a bigger lithium ion battery.

Electric scooter

Electric vehicles make sense for fleet operators as they typically can be charged overnight. This electric scooter, used by the Massachusetts State Police, can go 20 miles per hour and is used for patrolling streets.

Mass Port nat gas

Hybrids' power trains are certainly not the only technology being used by fleet operators. Massachusetts airport authority Massport has been operating these Honda sedans, which run on natural gas. It also has fleets of buses that transport people between terminals and to public transportation. Massport is now looking to retire its fleet of natural gas buses and exploring alternative technologies.

Propane truck

Fleet operators are also using propane-powered vehicles, such as this Ford pickup truck. Propane engines have been fitted onto school buses and are attractive because the fuel is cheaper than diesel and burns cleaner, too.

Fuel cell equinox

General Motors showed off a Chevy Equinox SUV that runs on a hydrogen fuel cell. The company is testing 100 of these with consumers and businesses that are able to refuel at hydrogen stations. Seen here is the fuel cell stack, which chemically converts hydrogen into electricity. In its next generation, GM plans to shrink the fuel cell stack to a smaller size--because of the tight fit, the regular 12-volt battery and windshield cleaning fluid container had to be moved to the back of the car. Another significant challenge for fuel cell vehicles is hydrogen storage, which limits the driving range of these vehicles to less than their gasoline counterparts.

VanGo van

There's a great deal of attention to lithium ion batteries because they are lighter and deliver more power than traditional lead acid batteries. But there are a number of companies making improvements on lead acid chemistry and using these batteries in fleet trucks. This converted van from Vantage uses both lead acid and lithium battery packs to get a 40- to 80-mile range. The top speed is only about 30 miles per hour, but it's street legal and is suitable for in-town driving.

Lead acid city car

A retailer in the Boston area is marketing this Miles Electric utility truck as a passenger vehicle that runs entirely off lead acid batteries. The range is limited to 80 miles or so and its top speed is only 25 miles per hour. Newer battery technologies promise better range and top speed but will be more expensive, said Paul Elwood of Electric City Cars. This car costs $20,000, but Elwood says tax incentives bring the cost down to $10,000.

Roopod

Most of the vehicles at the AltWheels Fleet Day were experimental or modified versions of existing models. But there were a few concept cars, including this Roopod prototype. This three-wheel microcar uses an aluminum body to weigh only 500 pounds. It runs on a diesel engine using waste vegetable oil to get an estimated 120 miles per gallon.

MIT Porsche

Engineering students from the Massachusetts Institute of Technology converted a Porsche 914 to run on lithium ion batteries. This bank of batteries is just one of three locations that hold the batteries--they are also in the trunk and in the middle of the car, where the gas engine usually goes. Because electric vehicles have full torque at all speeds, this car only uses second gear until it gets to 60 miles per hour.